Cooling arrangement for electric furnace



1960 R; J. GARMY 2,950,094

COOLING ARRANGEMENT FOR ELECTRIC FURNACE. Filed April 8, i957 5 Sheets-Sheet 1 114 121 INVENTOR.

114," POBEETJGARMX BYZU". 4/. w

ATTORNEK Aug. 23, 1960 I R. .1 GARMY 2,950,094 COOLING ARR];ilGliilwliiN'I FOR ELECTRIC FURNACE v s Shee ts-Sheet 2 Filed April 8, 1957 INVENTOR. ROBE/PR1 GAR/7). BYwT JV.

ATTORNEK Aug. 23, 1960 R; J. GARMY' 2 95 ,09 I COOLING ARRANGEMENT FOR ELECTRIC FURNACE I 5 sheets-sheet 3 Filed April 8, 1957 INVENTOR.

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Arrow/5K CGQLHIG ARRANGEMENT FOR ELECTRIC FURNACE Robert James Garmy, Canton, Ohio, assignor to Republie Steel Corporation, Cleveland, Ohio, a corporation of New Jersey Filed Apr. 8, 1957, Ser. No. 651,328

7 laims. (Cl. 257-208) This application is a continuation-in-part of my copending application, Serial No. 391,549, 1 led November 12, 1953, now Patent No. 2,800,519, granted July 23, 1957, entitled Method and Apparatus for Forming Inge-ts.

The present invention relates to improved apparatus for cooling and thereby controlling the temperature of furnaces, crucibles, or the like.

This invention, and the apparatus described herein, is of particular utility in connection with the formation of ingots of difiicultly meltable metals, such as titanium, Zirconium and the like. Moreover, the invention and the apparatus are of broader general utility, in connection with the manufacture of low impurity metals and alloys generally. For example, this apparatus has been used successfully to manufacture ingots of high purity steels.

As explained in my copcnding application, the formation of ingots from metals such as titanium and zirconium presents very diificult problems. The metal must, of course, be melted in order to form the ingot. The melting points of such metals are very high, in the neighborhood of 3l003300 F. It is diilicult even to raise a substantial volume of material to such a temperature. Furthermore, it is difiioult to obtain such a temperature without running the risk of exceeding it, with consequent danger to personnel and risk of destruction of the apparatus used. At high temperatures, even considerably below their melting points, titanium and zirconium are very active chemically and will unite with almost any other element with which they come in contact. They are especially apt to be oxidized at such temperatures if there is any oxygen present. It has been proposed to construct of copper those parts of a melting furnace which contact the titanium. However, the melting point of copper (about 1981 F.) is substantially lower than that of titanium, and the temperature at which copper loses its working strength is even lower. It is therefore necessary to cool the copper parts of the furnace, usually with cooling jackets or the like, through which a flow or" water or other suitable coolant is directed.

In this application, the term Water jacket is used in many instances to describe the jacket through which the coolant flows, and the coolant is in most instances identified as water. The term water jacket is conven tional, regardless of the specific coolant used. It will be understood, however, by those skilled in the art, that this invention is not limited to the use of water or any other specific coolant, but that any of several commercially available coolants could be used successfully in jackets constructed in accordance with the invention.

Because of the extremely high temperatures involved, the construction of effective water jackets for such furnaces, crucibles and the like presents difiicult problems. It is essential that the water be circulated constantly to all parts of the jacket, in order to prevent any possibility of boiling of the water in the jacket. To the same end, it is desirable that the volume of water in the jacket at Patent Patented Aug. 23, W60

any time be minimized and that the rate of flow of water through the jacket be kept high.

Present preferred melting practice involves the use of arc melting, employing either non-consumable or consumable electrodes, which provides an intense high temperature source of heat within the confined volume of the melting crucible. It is a specific objective of this invention to provide a means for confining the high temperature refractory melt in such manner as, (a) to redues to a minimum the natural hazard involved; (b) to avoid contamination of the melt; and (0) to accomplish this with such means as may be relatively easily handled in preparation for the melting operation and during the operations subsequent to melting including the removal and handling of the ingot of melted material. Such a construction necessarily requires, and the subject invention provides, a means for effectively and rapidly extracting heat throughout the entire boundary region of the melt. I havefound that the most efiicient way of accomplishing this is to provide a thin walled, heatconductive inner crucible liner of material such as copper, surrounding the outer surface of said liner with a heat extracting liquid such as water and, further providing means for assuring forced circulation of the heat extracting fluid in order to prevent development of local overheated regions which could possibly lead to incipient melting or burn through of said liner. It is a further object of the invention to provide a structurally strong construction which will support the relatively heavy ingot and avoid distortion because of the widely different teniperature conditions to which various parts of the construction are exposed during the entire melting operation.

Since the thin-walled liner is subject to temperatures near its melting point, it may tend to distort during use. This distortion may take the form of an outward bulge. The water jacket space just outside the liner is made thin in order to minimize the volume of water inside the jacket. Since an outward bulge of the liner might tend to narrow and constrict the jacket space and thereby impede the flow of water therethrough, it is desirable that such outward bulges of the crucible liner be minimized by providing reinforcing or supporting structure.

An object of the present invention is to provide improved water jacket apparatus of the type described.

Another object is to provide improved water jacket structure for a cylindrical crucible or the like.

A further object is to provide an improved water jacket structure for the base or end wall of such a crucible.

Another object is to provide an improved Water jacket structure for the side wall of such a crucible.

A further object is to provide an improved water jacket structure for cooling the corner between the see and side walls of such a crucible.

The foregoing and other objects of the invention are attained, in the modifications described herein, by pro-- viding a base water jacket for a cy indrical crucible, said base jacket including spaced upper and lower plates, a plurality of inlets located at angularly spaced intervals and radially spaced from the axis of the crucible and from the periphery of the jacket. Each inlet is provided on its-inner end with an elbow ending in an arm projecting parallel to the plates and located substantially midway between the plates. In one modification, all the elbows are directed'tangentially with respect to the radii extending to them from the axis. In another modification, the elbows are directed somewhat outwardly from the tangential angle. In both modifications, the elbows are directed so that they are effective to introduce the water with a swirling motion. Also, in both modifications, a single outlet opening for the jacket is provided at the center of the lower plate. These locations of the inlets and the outlet ensure that the jacket fills from the periphery in toward the center, so that all air in the jacket is forced out and the jacket runs full of water. This Water in the base jacket helps to support the load of the ingot formed in the crucible. In both modifications, one of the two plates is provided with a series of arcuate internal ridges extending toward the other plate. These ridges are effective when the crucible is heavily loaded to transfer part of the load from the upper to the lower plate and thereby to prevent restriction or" the water jacket space by distortion of the upper plate due to the weight of the material in the crucible.

The cylindrical side wall of the crucible is provided with a water jacket comprising an outer wall spaced outwardly from the crucible wall. A series of peripherally spaced inlets are provided around the outer wall adjacent its lower end. A series of peripherally spaced outlets are provided around the outer wall adjacent its upper end. At each outlet, a U-shaped guard extends between the inner and outer walls, with the open end of the U upward, and is effective to prevent water from reaching the outlet except from above. These guards ensure that the side wall jacket is always full when the furnace is in operation.

In one modification of the invention, helical reinforcing ribs are located on the inside of the outer jacket Wall, and abut closely against the inner crucible Wall. These ribs limit or prevent any outward bulging of the inner crucible wall or liner. Their helical form enables them to perform their function without impeding the flow of water through the jacket.

Other objects and advantages of the invention will be come apparent from a consideration of the following description and claims, taken together with the accompanying drawings, in which:

Fig. 1 is a view, partly in elevation and partly in sec tion, of a crucible having water jackets constructed in accordance with the invention;

Fig. 2 is a horizontal sectional view, taken on the line 11-11 of Fig. 1, showing the construction of the inlets and outlet of the base water jacket;

Fig. 3 is a horizontal sectional view, taken on the line IlI--III of Fig. 1;

Fig. 4 is a developed inside elevational view of the outer wall of the side water jacket, showing the inlet and outlet locations and associated shield structures;

Fig. 5 is a view similar to Fig. 4, showing another modification of the side wall Water jacket; and

Fig. 6 is a view similar to Fig. 2, showing another modification of the base water jacket.

Figs. 1 to 4 The drawings illustrate an electric furnace including a generally cylindrical shell 1 having its axis vertical and provided with an annular base plate resting on a floor (not shown). The shell base plate 2 has a central opening 2a which is inserted the upper end of a crucible 4.

The crucible 4 comprises a generally cylindrical crucible shell including an outer shell 41; of steel and a copper liner 4b. Alternatively, the liner 4b might be constructed of molybdenum, in which case the liner would have a higher operating temperature, and conse quently a larger body of molten metal within the furnace would be possible. The shell 4a and liner 4b are concentric and are spaced apart at their top ends by spacers 5 and at their bottom ends by a flange 6 so as to define a water jacket 40 between them. The water jacket 4:: is provided with a number of peripherally spaced water inlets 104. It should be noted that the inlets 104 consist of short pipe sections set at an angle to radial lines drawn from the center of the crucible. The effect of this angular setting of the inlets 104 is to produce a flow of water through the water jacket in a more-o'r-less helical path. The water is betterdistributed by arranging the inlets in this manner, so that the cooling of the shell is more uniform and hot spots do not develop. Near the upper end of the shell, it is provided with a number of water outlets 105, best seen jin Fig. 4, one outlet being shown in detail in cross-section in Fig. 1. In Fig. 4 it may be seen that each outlet is surrounded by a U-shaped shield 106, open at the top. The shields 1% prevent any water from entering the outlets except through the upper ends of the shield. Consequently, all the water must flow close to the upper end of the water jacket before it can pass a shield 166 and enter an outlet. In this manner the cooling of the complete crucible shell all the way to the upper end is ensured.

On the outside of the crucible shell 4 near its upper end there is provided a built-up conduit 107 to receive the water flowing through the outlets 105. The conduit iii? is provided with a suitable drain connection 108.

The upper side of the built-up conduit 187 is formed by a flange 169 whose upper face is adapted to engage the lower face of a centering ring 102 so as to establish the position of the upper end of the crucible 4 during operation of the furnace. Above the flange 169, there are welded on the outer surface of the shell 4a a number of ribs 110, best seen in Fig. 1. These ribs fit loosely within the opening 2a in the plate 2 and center the crucible 4 in accurate alignment with the shell 1.

The various parts which make up the crucible shell assembly are preferably welded together, as shown in the drawings.

The lower end of the crucible shell 4- rests on and is attached to a base plate assembly 111, including an upper plate 112 and a lower plate 113. The peripheral flange 6 on the lower end of the shell 4 is bolted to the lower base plate 113 by means of bolts 115. The upper and lower base plates define between them a water jacket space 116. Three inlets 117 are provided through the lower base plate 113, angularly spaced as shown in Fig. 2. Each inlet 117 is provided with an elbow nozzle 1118 directed at an angle to the radial lines from the center of the crucible so that the water flows tangentially and outwardly from the nozzles 113 and circulates around the Water jacket space 116 with a swirling motion. A central water outlet opening 119* is provided. These locations of the inlets 118 and outlet 119 ensure that, when placed in service, the jacket fills from the outside toward the central outlet, thereby forcing all air out and maintaining the jacket completely full of water under all operating conditions. The water in the base jacket is efiective to transfer part of the load due to the forming ingot to the lower base plate, from which it is transferred to the underlying support. Distortion of the upper base plate by the load, and possible resultant destruction of the water jacket are thereby prevented.

The upper base plate 112 is provided on its under surface with four ribs 112a, which also aid in supporting the central portion of plate 112 and the ingot resting on it. These ribs 112:: have their edges streamlined, as shown in Fig. 2, to avoid creation of turbulence in the cooling water swirling toward the center outlet 119.

It should be noted that, when the crucible is assembled, as shown in Fig. 1, the upper surface of the upper base plate 112 is in a horizontal plane above the lower end of the water jacket 4c in the crucible shell. The water jacket 4c is thereby effective to cool the entire length of the ingot and the welded joints at the base of the crucible shell are protected from the heat of the ingot.

The crucible shell 4 is provided with upper and lower machining bands 120, to provide locating surfaces for machining operations during manufacture or repair of the crucible.

The upper and lower base plates 112 and 113 are both formed of copper. The lower base plate 113 is provided with an annular groove 113a, to receive an O-ring which efiectively seals the base plate assembly against leakage of water when the two plates 112 and 113 are together.

When the furnace is in operation the crucible and more specifically the base plate assembly rests on a supporting frame 121, more completely described in my This figure illustrates a modified form of side well water jacket. In this figure, those parts which correspond to their counterparts in Fig. 4 have been given the same reference numerals and will not be further described.

The structure of Fig. 5 diifers from that of Fig. 4 by having a series of steel ribs 122 welded on the inner sur face of the outer shell 4a. When these ribs are in their correct positions, rather than in the flat developed view of Fig. 5, the ribs are helical. Their inner surfaces are machined, and they are dimensioned to abut closely against the inner crucible 4b. These ribs reinforce the thin shell 4b, and prevent it from bulging outwardly so as to restrict the path of flow of water through the side wall water jacket. By virtue of their helical contour, they perform their function without themselves introducing any substantial restriction of that flow path.

Fig. 6

This figure is generally similar to Fig. 2 and illustrates a modified arrangement of water inlets for the base water jacket. In the arrangement of Fig. 6, there are four inlets 123, spaced evenly and angularly about the vertical axis of the water jacket. Each inlet 123 is provided on its inner end with an elbow directed tangentially withrespect to the water jacket axis. a

The arrangement shown in this figure is effective to deliver the water at a larger number of spaced points and thereby to provide more even distribution than the three inlet arrangement illustrated in Fig. 2. Also, the tangential direction of the ribs provides a somewhat smoother flow of the water inside the jacket, since the water jet from each inlet impinges on the peripheral wall at a smaller angle.

While I have shown and described certain preferred embodiments of my invention, other modifications thereof will readily occur to those skilled in the art, and I-therefore intend my invention to be limited only by the appended claims.

What is claimed is:

1. A crucible adapted to enclose heat producing means, comprising vertically extending cylindrical concentric inner and outer shells separated by an annular space, means extending across the ends of said space and connected to said shells to close said space at said ends so as form with said shells a water jacket structure, the inner shell at its lower end extending a substantial distance downwardly beyond the lower end of said annular space and within said space closing means at said lower end, means for effecting circulation of coolant through said space of said water jacket structure, base closure means extending across and closing the lower end of the crucible space within said inner shell and having a peripheral upper face surface engaging the lower end of said water jacket structure, said base closure means including an upper horizontally disposed wall having a portion adjacent and forming a shoulder with said upper peripheral face surface of said base closure means, said portion projecting upwardly within and in heat conducting engagement with said downwardly extending end of said inner shell, said portion of said upper wall at its periphery projecting upwardly to a level above the lower end of said shell water jacket space, said closure means including a lower horizontally disposed wall spaced from said upper horizontally disposed wall and defining therewith a base water jacket space, inlet means for delivering coolant into said base water jacket space, and outlet means for conducting coolant from said base water jacket space, the spacing apart of said upper and lower walls of said base closure means being restricted to insure continuous flow from said inlet means to said outlet means.

2. A crucible adapted to enclose heat producing means,

comprising vertically extending cylindrical concentric inner and outer shells separated by an annular space, means extending across the ends of said space and connected to said shells to close said space at said ends so as to form with said shells a water jacket structure, the inner shell at its lower end extending a substantial distance downwardly beyond the end of said annular space, a plurality of water inlets opening into said space and spaced around the periphery of said water jacket structure adjacent the lower end of said space, a plurality of water outlets opening outwardly from said space and spaced around the periphery of said water jacket structure adjacent but spaced from the upper end of said space, and a plurality of U-shaped shields respectively associated with said water outlets, each shield extending across said annular space between said shells and partially encircling one of said outlets with the open side of the U upward and with the upper edge of the U above said outlet and spaced downwardly from the upper end of said annular space so as to insure flow of the water upwardly and over the upper ends of the U and downwardly to the associated inlet and so as to prevent flow of water from the annular space adjacent the outlet directly to the outlet.

3. A crucible including a base closure having upper and lower walls spaced apart vertically and defining a generally cylindrical water jacket space between them, said water jacket space having a diameter substantially greater than its axial length, a plurality of water inlets extending through said lower wall into said water jacket space at points spaced radially from the axis of the cylindrical jacket and substantially to the middle of said axial length, said inlets being provided on their inner ends with nozzles directed at angles to the radial lines extending thereto from said axis to circulate the water in said jacket with a swirling motion, a water outlet provided in said lower wall and disposed at said axis and opening axially from said cylindrical jacket, and means providing a plurality of unobstructed generally radially extending paths spaced about said axis for flow of cooling water delivered through said inlets to said outlet.

4. A crucible adapted to enclose heat producing means, comprising vertically extending cylindrical concentric inner and outer shells separated by an annular space, means closing the ends of the space and cooperating with the shells to define a shell water jacket shorter in length than the inner shell, a base closure comprising upper and lower plates having central portions spaced apart and defining 'a generally cylindrical base water jacket between them, said base water jacket including a portion of said upper base plate projecting within the lower end of said inner shell and to a substantial distance above the lower end of the shell water jacket, so that the entire end portion of the inner shell exposed to said heat producing means is directly cooled by said shell water jacket, said base water jacket having a diameter substantially greater than its axial length, a plurality of water inlets extending through said lower plate into said base water jacket at points spaced radially from the axis of the base jacket and substantially to the middle of said axial length, and inlets being provided on their inner ends with nozzles directed at angles to the radial lines extending thereto from said axis to circulate the water in said jacket .with a swirling motion, and a water outlet provided in said lower plate and disposed at said axis and opening axially from said cylindrical jacket.

5. A crucible adapted to enclose heat producing means, comprising vertically extending cylindrical concentric inner and outer shells separated by an annular space, means extending across the ends of said space and connected to said shells to close said space at said ends so as to form with said shells a water jacket structure, the inner shell at its lower end extending a substantial distance downwardly beyond the lower end of said annular space and within said space closing means at said lower end, a plurality of water inlets opening into said annular space through said outer shell and spaced around the periphery of said water jacket structure adjacent the lower end of said annular space, each of said inlets comprising a pipe extending generally tangentially with respect to said annular space, a plurality of water outlets opening outwardly from said annular space through said outer shell and spaced around the periphery of said water jacket structure adjacent but spaced from the upper end ofsaid annular space for withdrawing water therefrom, a plurality of circumferentially spaced helical reinforcing ribs supported between said inner and outer shells and abutting the outer surface of said inner shell to inhibit outward bulging of said inner shell, said ribs having their lower ends disposed above said inlets, said inlets cooperating with said ribs to create flow of water about the axis of said shells and upwardly through said annular space along generally helical paths, and a plurality of shields disposed in said annular space and extending between said shells, each of said shields being located adjacent and extending about one of said outlets at the lower side thereof so as to prevent flow of water moving upwardly in said annular space directly to said outlet, said shields being spaced from said upper end of said annular space and being open at the upper side thereof to provide for flow of the water to the upper end of said annular space and thence downwardly within said shields to said water outlets, said ribs having their upper ends below said shields so as to effect flow of the water from said helical paths upwardly between said shields.

6. A crucible adapted to enclose heat producing means, comprising vertically extending inner and outer concentric cylindrical shells separated by an annular space, means closing the ends of the space and cooperating with the shells to define a shell water jacket shorter in length than the inner shell, a plurality of water inlets spaced around the periphery of the water jacket adjacent its lower end, each said inlet comprising a pipe section extending generally tangentially with respect to said shell, said inlets cooperating to create a flow of water upwardly through said jacket along a generally helical path, a plurality of circumferentially spaced helical reinforcing ribs fastened on the inner surface of the outer shell and abutting the outer surface of the inner shell to inhibit outward bulging thereof, said ribs having their lower ends above said inlets, a plurality of water outlets spaced around the periphery of the water jacket adjacent but spaced from its upper end, and a plurality of shields, each located adjacent one'of said outlets and preventing flow of water thereto except from above, said shields being effective to ensure circulation of water about the upper end of the water jacket, said ribs having their upper ends below said shields, a base closure comprising upper and lower plate members having central portions spaced apart and defining a base water jacket, said base water jacket including a portion of said upper plate member projecting within the lower end of said inner shell and a substantial distance above the lower end of the shell water jacket, so that the entire end portion of the inner shell exposed to said heat producing means is directly cooled by said shell water jacket, said base water jacket having a diameter substantially greater than its axial length, a plurality of water inlets extending through said lower plate into said base water jacket at points spaced radially from the axis of the cylindrical jacket and substantially to the middle of said axial length, said inlets being provided on their inner ends with nozzles directed at angles to the radial lines extending thereto from said axis, to circulate the Water in said jacket with a swirling motion, and a water outlet at the center of said lower plate and opening axially from said base water jacket, a plurality of generally arcuate ribs fixed on one of said base plate members and abutting the other base plate member, said ribs being effective to support partially said upper base plate member and the charge of material to be heated resting thereon, said ribs being concentric with said base plate members and streamlined along their length, to avoid turbulence in the water flowing around them.

7. A crucible adapted to enclose heat producing means, comprising a base plate including inner and outer plate members having central portions spaced apart and defining a cylindrical. base water jacket having a diameter substantially greater than its axial length, a plurality of water inlets extending through the central portion of said lower plate into said base water jacket at points spaced radially from the axis thereof and substantially to the middle of said axial length, said inlets being provided on their inner ends with nozzles directed generally tangentially with respect to said axis to circulate the water in said jacket with a swirling motion, a water outlet at the center of said central portion of said lower plate and opening axially from said cylindrical jacket, and a plurality of circumferentially spaced arcuate ribs concentric with each other and with said outlet, said ribs being fixed on one of said base plate members between said inlets and said outlet and abutting the other base plate member, said ribs being effective to support partially said upper base plate and the charge of material resting thereon, said ribs being concentric with said base plates and streamlined along their length, to avoid turbulence in the swirling Water flowing around them, the spaces between said ribs permitting the flow of water from said inlets to said central outlet.

References Cited in the file of this patent UNITED STATES PATENTS 733,191 Griesser Iuly 7,1903 1,253,766 Alden Ian. 15, 1918 1,919,179 Wiltsch July 18, 1933 2,277,526 Mojonnier et al. Mar. 24, 1942 2,541,764 Herres et a1 Feb. 13, 1951 2,640,860 Herres June 19, 1953 FOREIGN PATENTS 221,188 Great Britain Aug. 27, 1925 OTHER REFERENCES Iron Age, Feb. 24, 1944, Continuous Castings, Lip pert (see page 65, column 1, first full paragraph).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent N0 2 950 094 August 23 1960 Robert James Garmy It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3 line 57 after "2a" insert we in ===9 Signed and sealed this 11th day of April 1961,

(SEAL) Attest: ERNES w. SWIDER ARTHUR W CROQKER Attesting Oflicer Ac ing Commissioner of Patents 

